AnswerDeb,
What you will want to do is check for voltage at the heating element with the unit running. Unplug the unit and pull one wire from the side of the heater that goes to the thermostat. Plug the unit back in and turn the dryer on. Test for 120 vac at the terminal where you disconnected the wire. If 120 vac is present then test the loose wire for 120 vac. If either of these do not have 120 vac then you need to trace back to the source and determine if it is the thermostats, timer or motor that is causing loss of power. If there is 120 vac at the loose wire but not on the terminal for the heater then the heater is most likely the cause but trace the circuit back by first testing the other terminal with the wire still connected on the heater. If 120 vac is present there then the heater would be the cause.